Elevator systems include a variety of components for controlling movement of the elevator car. For example, an elevator drive is responsible for controlling the motor that causes movement of the elevator car. An elevator safety chain is associated with the elevator drive to prevent the motor from causing the elevator car to move if the elevator car doors or any of the doors along the hoistway are open, for example. The safety chain operates to prevent power flow to the drive and the motor.
Allowing the safety chain to control whether power is supplied to the elevator drive and the motor has typically been accomplished using high cost relays. Elevator codes require confirming proper operation of those relays. Therefore, relatively expensive, force guided relays are typically utilized for that purpose. The force guided relays are expensive and require significant space on drive circuit boards. Force guided relays are useful because they allow for monitoring relay actuation in a fail safe manner. They include two contacts, one of which is normally closed and the other of which is normally open. One of the contacts allows for the state of the other to be monitored, which fulfills the need for monitoring actuation of the relays.
Elevator system designers are always striving to reduce cost and space requirements. Force guided relays interfere with accomplishing both of those goals.